Marek J, Vévodová J, Smatanová I K, Nagata Y, Svensson L A, Newman J, Takagi M, Damborský J
Laboratory of Biomolecular Structure and Dynamics, and Department of Inorganic Chemistry, Faculty of Science, Masaryk University, Kotlárská 2, CZ 611 37 Brno, Czech Republic.
Biochemistry. 2000 Nov 21;39(46):14082-6. doi: 10.1021/bi001539c.
The haloalkane dehalogenase from Sphingomonas paucimobilis UT26 (LinB) is the enzyme involved in the degradation of the important environmental pollutant gamma-hexachlorocyclohexane. The enzyme hydrolyzes a broad range of halogenated cyclic and aliphatic compounds. Here, we present the 1.58 A crystal structure of LinB and the 2.0 A structure of LinB with 1,3-propanediol, a product of debromination of 1,3-dibromopropane, in the active site of the enzyme. The enzyme belongs to the alpha/beta hydrolase family and contains a catalytic triad (Asp108, His272, and Glu132) in the lipase-like topological arrangement previously proposed from mutagenesis experiments. The LinB structure was compared with the structures of haloalkane dehalogenase from Xanthobacter autotrophicus GJ10 and from Rhodococcus sp. and the structural features involved in the adaptation toward xenobiotic substrates were identified. The arrangement and composition of the alpha-helices in the cap domain results in the differences in the size and shape of the active-site cavity and the entrance tunnel. This is the major determinant of the substrate specificity of this haloalkane dehalogenase.
少动鞘氨醇单胞菌UT26的卤代烷脱卤酶（LinB）是参与重要环境污染物γ-六氯环己烷降解的酶。该酶能水解多种卤代环状和脂肪族化合物。在此，我们展示了LinB的1.58 Å晶体结构以及LinB与1,3 - 丙二醇（1,3 - 二溴丙烷脱溴产物）在酶活性位点的2.0 Å结构。该酶属于α/β水解酶家族，包含一个催化三联体（Asp108、His272和Glu132），其呈先前诱变实验提出的类似脂肪酶的拓扑排列。将LinB的结构与自养黄色杆菌GJ10和红球菌属的卤代烷脱卤酶结构进行了比较，并确定了其对外源底物适应性所涉及的结构特征。帽状结构域中α - 螺旋的排列和组成导致了活性位点腔和入口通道在大小和形状上的差异。这是该卤代烷脱卤酶底物特异性的主要决定因素。
